The present invention relates to a seat belt retractor installed in a vehicle such as an automobile, a working vehicle, or the like for winding up a seat belt to restrain and protect an occupant, and relates to a seat belt apparatus with the seat belt retractor. More particularly, the present invention relates to a seat belt retractor for winding up a seat belt onto a reel by driving torque of a motor, and relates to a seat belt apparatus with the seat belt retractor.
A seat belt apparatus installed in a vehicle seat is an apparatus for restraining rapid movement of an occupant due to acceleration caused by a vehicle collision, thereby providing safety of the occupant. The seat belt apparatus generally comprises a seat belt (webbing), a tongue attached to the seat belt, a buckle mounted to a vehicle seat for engaging the tongue, a retractor, and the like.
The retractor houses the seat belt by winding up the seat belt onto a take-up member (reel, bobbin, or spool) by urging force of a spring. In addition, the retractor locks the take-up member from rotating in the belt withdrawing direction with an emergency locking mechanism (ELR mechanism) upon a vehicle collision, i.e. when an impact acts on the vehicle. When the seat belt is locked, the occupant rapidly moving forward is restrained.
In a conventional seat belt retractor, a rotational speed of a motor is reduced and transmitted to a take-up member by a power transmission mechanism of a gear train composed of a plurality of gears, so that a seat belt is wound up by a take-up member (i.e. motor retractor). In such a seat belt retractor, a detection device is further provided for detecting a possible collision of a vehicle, so that the motor winds the seat belt stepwise according to a possibility of a collision (for example, Patent Reference 1).
Patent Reference 1: Japanese Patent Publication (Kokai) No. 2000-52925
In the conventional seat belt retractor, only when a possible collision of the vehicle is detected, the motor operates at just two winding levels to tighten the seat belt according to a possibility of a collision. An individual tends to have a wide range of preference regarding tightness of a seat belt during normal driving. For example, a person may like to fasten the seat belt tightly because of sense of safety, while another person may like to fasten the seat belt softly because of comfort. In the conventional seat belt retractor, it is difficult to control a degree of the tightness according to individual preference.
In view of the problems described above, an object of the present invention to provide a seat belt retractor and a seat belt apparatus capable of adjusting tension of a seat belt according to individual preference.
Further objects and advantages of the invention will be apparent from the following description of the invention.